I have heard from some people that it is pointless to takes sides in the unrest in Iran because this is essentially a feud within the power structure. The leaders of the opposition are mostly people who have been part of the Islamic government in one way or another for decades, so why support their challenge to Ahmadinejad?
There are two reasons why ths is important regardless.
Domestically, anything that disrupts the smooth working of the Islamic regime is good. Anything that makes Ahmadinejad look weak, ineffective and hated is positive. He is a dangerous man and the world needs to know that many in Iran think so too. These events, and the certainty that the vote was fraudulent, weaken the legitimacy of the Islamic state. Ayatollah Khamenei says this is a “divine assessment,” which is a pretty lofty thing to call ballot box stuffing.
Internationally the blacker the mark on the regime this is the better. The international community is moving far too slowly to negate the Iranian nuclear threat and respond to other provocations from Tehran. If this weakens Iran’s standing then that’s a positive thing. That being said I have little hope that the Obama Administration will take advantage of this opportunity in any way. The anemic response thus far shows not just caution but weakness. One gets the idea that the administration would just as soon this all go away so they can get back to business. In some ways it’s like Hungary 1956, Czechoslovakia 1968.
The big picture is that this destabilizes the regime, shows what’s possible, inspires revolutionary consciousness — it’s all for the good, and the more the better. It tells the world that the people of Iran are not happy under the heel of the Islamists.